Apparatus for injecting solid particulate material into a metallurgical furnace



3,1 78,165 LATE NACE April 13, 1965 R. E. ZIMMERMANN APPARATUS FOR INJECTING SOLID PARTICU MATERIAL INTO A METALLURGICAL FUR Filed March 21, 1963 INVENTOR ROBERT E. ZIMMERMANN 7?\ v Attorney United States Patent APPARATUS FOR INJEC'IING SOLHD PARTICU- LA'E'E MATERTAL INTO A METALLURGICAL FURNACE Robert E. Zimmerman, Genoa, Italy, assignor to Koppers Company, Inc., a corporation of Delaware Filed Mar. 21, 1963, Ser. No. 266,857 8 Claims. (Cl. 26628) This invention relates to the construction and operation of apparatus for injecting solid particulate material into a metallurgical furnace and more particularly the invention relates to the method and apparatus for uniformly delivering controlled amounts of particulate material dispersed in a gas to the tuyere zone of a blast furnace.

The principal fuel presently employed in a blast furnace is metallurgical coke made from a mixture of high volatile and low volatile metallurgical coals. Coke is expensive and represents a substantial portion of the costs incurred in the ore reduction process. Numerous attempts have been made in the past to substitute a less expensive fuel for the metallurgical coke. Less expensive fuels have been added to the charge as it is fed into the top of the furnace. The admixture of less expensive fuels with the charge has met with little success. Metallurgical coke serves not only as a fuel in the ore reduction process, but also supports the heavy burden within the furnace, and its porosity provides outlets for the blast gas through the burden in the furnace. The addition of less expensive fuels to the charge reduces the effectiveness of the metallurgical coke in either one or both of the above functions and results in erratic blast furnace operation.

The addition of less expensive fuels to the tuyere zone of the blast furnace has also been attempted in the past. Liquid or gaseous fuels such as fuel oil and natural gas have been considered as a supplemental fuel for the blast furnace. Economic studies have shown, however, that the injection of nonmetallurgical coal as a supplemental fuel is from four to six times cheaper than either the liquid fuel oil or natural gas. A process, therefore, to inject nonmetallurgical coal particles into the tuyere zone of a blast furnace provides substantial economic incentives over either liquid fuels or gaseous fuels.

There are inherent difiiculties, however, in introducing particulate material such as coal particles into the tuyere zone of a blast furnace. The blast furnace has a substantial internal pressure and the coal particles must be introduced at a pressure substantially higher than the internal pressure of the blast furnace. A suitable manner for conveying the coal particles from a coal storage device to the blast furnace is to fluidize the coal particles in a gas stream and introduce the fluidized stream into the tuyere zone of the blast furnace. The air stream must, however, be at a sufficiently high velocity to maintain the coal particles in a fluidized state. The air must also be at a pressure greater than the pressure within the blast furnace.

In the known processes for introducing particulate material into a pressurized gas stream the particulate material is transferred from a receiver at atmospheric pressure to the air stream at the elevated pressure. Rotary type feeders have been suggested in the past to receive the particulate material at atmospheric pressure and introduce the particulate material into the high pressure gas stream. The high pressure required in the air transfer line to the blast furnace would require elaborate and expensive sealing devices on the rotary feeders. The high pressure differential between the feeder inlet and outlet would further subject the rotary feeder to undue stresses and therefore limit the useful life of the feeder. A process where the inlet and outlet of the rotary feeder are subjected to substantially the same pressures would elimi- 3,178,165 Patented Apr. 13, 1965 ice hate the above discussed problems and provide a metering device which could accurately supply preselected quantities of particulate material such as coal particles to a moving air stream.

Briefly, the invention herein disclosed provides a method and apparatus for introducing coal particles into the inlet of a rotary feeder at a pressure substantially equal to the pressure of the gas stream. The invention further includes means for positively removing the coal particles from the rotary feeder as the rotary feeder revolves past the discharge port.

Accordingly, the principal object of this invention is to provide an improved method and apparatus for injecting solid particulate material into a blast furnace wherein the particulate material is fed to the feeder device at an elevated pressure.

Another object of this invention is to provide an improved process for injecting solid particulate material into a blast furnace wherein the feeder device is not subjected to the high pressure differential encountered where the feeder inlet is at atmospheric pressure.

These and other objectives achieved by this invention will become apparent as this description proceeds in connection with the accompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic sectional elevation of an ore reduction furnace and the improved injection apparatus.

FIGURE 2 is a View in section taken along the lines IIII of FIGURE 1.

FIGURE 3 is an enlarged schematic elevation view of the rotary feeder for introducing the particulate coal into the air stream.

FIGURE 4 is a view in section taken along the lines IVlV of FIGURE 1 illustrating the feed bins and hopper in section.

Referring to FIGURE 1 of the drawings, a coal bucket 10 is suitably supported by a monorail 12 above the storage hopper 14. The coal bucket 10 is arranged to maintain a supply of suitably sized coal particles within the hopper 14. The hopper bottom wall has a plurality of inclined sections 16 with circular openings 18 therein. The inclined sections 16 are arranged to feed the particulate coal into a plurality of pressurized receiving bins 20. A bell valve or gate 22 seals the circular openings 18 in the bottom wall of hopper 14. The hopper 14 has an open top and has an inclined side wall 24. With this arrangement high moisture coal particles are fed by gravity to the openings 18. Below the hopper 14 there are a plurality of pressurized bins 20 each having inclined bottom walls 26 similar to the bottom wall 16 of hopper 14. The bottom walls 26 have circular openings 28 therein which are sealed by a bell valve or gate 30 similar to the valve 22. Both valves 22 and 30 have upwardly extending shafts 32 and 34 connected to suitable actuating means (not shown). The bell valves 22 and 30 are ar ranged to move downwardly to provide annular openings between the respective valves and circular openings in the bottom walls of hopper 14 and bin 20.

The bin 20 has a cylindrical standpipe 36 extending downwardly therefrom. The standpipe 36 is arranged to receive particulate coal fed thereto through the opening 28 in bin 20. Both the bin 20 and the standpipe 36 are pressurized by air supplied through conduit 38. Control valves 40 and 42 are positioned in respective branch conduits 44 and 46 connecting conduit 38 to the bin 20 and standpipe 36. Valve 40 controls the pressure in bin 20 and closes conduit 44 when gate 22 is open and coal is being fed from hopper 14 to bin 20. Valve 40 remains open when gate 22 is closed to pressurize bin 20.

Valve 42 is arranged to control the pressure within the standpipe 30 so that the coal particles can be fed to 3 standpipe 36 from bin 28 in a suitable manner by opening the bell valve 30.

The standpipe 36 is connected to a rotary feeder generally designated by the numeral 48. The feeder is connected at its lower end to a common air header t) schematically illustrated in FIGURES 1 and 2. Although only a single rotary feeder 48 is illustrated in FIGURE 1, it should be understood that each of the standpipes 36 has a feeder 48 connected to its lower end portion and all of the feeders are connected to the header 59. The common header 5i and the plurality of feeders 48 are illustrated in FIGURE 2. Extending from the respective rotary feeders 48 are transfer conduits 52 arranged to convey the particulate coal and air from the respective feeders 48 t0 the tuyere zone of the blast furnace, as later explained.

There is a hot blast bustle pipe 58 positioned around the blast furnace 56 adjacent the tuyere zone 60. A plurality of hot blast tuyeres 62 are provided to introduce the hot blast gas into the tuyere zone 60. Suitable conduits 64 connect the bustle pipe 58 with the hot blast tuyeres 62.. Positioned between and slightly above the hot blast air tuyeres 62 are cold blast air tuyeres 66. The construction of the cold blast air tuyeres 66 is substantially the same as the hot blast air tuyeres 62. Conduits 52 are suitably connected to the cold blast air tuyeres 66 and terminate at end portions 68 within the blast furnace tuyere zone 60.

Each of the conduits 52 illustrated in FIGURE 2 is connected to a separate rotary feeder 48-. With this arrangement there is provided a separate feeder for each of the feed conduits 52 and, as will be later explained, it is possible to accurately control the amount of particulate coal fed to the blast furnace tuyere zone 69 by both controlling the relative rate at which the particulate coal is introduced into the feed conduits 52 from the metering device 48, and further by activating a selected number of the feeding devices 48.

The common header 50 supplies cold blast air to the respective branch conduits 52 and may be further preslsurized by means of a blower 70. Suitable throttling devices 72 may be positioned in the header 56 to control the air-coal mixture fed to the blast furnace tuyere zone 60. The cold blast air fed through header 50 and conduits 52 is controlled to provide a minimum amount of unheated blast air required to convey the particulate coal fed to the blast furnace tuyere zone 60 and thereby provide a maximum amount of hot blast air.

The rotary feeder 48 has a cylindrical body portion or casing 74 with a top inlet opening 76 and a bottom outlet opening 78. The inlet opening 76 has an annular flange 80 which secures the rotary feeder 48 to the standpipe 36. Suitable annular sealing means 82 is positioned between the standpipe 36 and the flange 89 to maintain a pressure seal therebetween. The cylindrical casing 74 has a pair of conduit sections 84 and 86 extending laterally therefrom adjacent the bottom opening 78. Portions of the casing 74 extend into the conduit sections 84 and 86 as illustrated in FIGURE 3. The conduit sections 84 and 86 have flanged end portions 88 and 90. Flange 88 connects conduit section 84 to common header 56 and flange 90 connects section 86 to feed conduits 52. The bottom wall 92 of the conduit section 84 has an upwardly extending protuberance or projection 94 which is arranged to provide eddy currents in the air flowing through the conduit sections 84 and 86, as will be later explained. Suitable end plates 75 and 77 (FIG. 2) are provided to close the ends of the casing 74 and provide an air tight chamber in the feeder 48. The inner wall of the cylindrical casing 74 has a liner 96 secured thereto. The liner is preferably of a selflubricating material. Teflon, a tetrafluoroethylene polymer, is a suitable material for the liner.

Rotor 98 is positioned within the cylindrical casing 74 and is supported on shaft 100 for rotation therewith. The rotor 98 has a plurality of radially extending arms 102 whieh form pockets 104 therebetween.

The radial end portions of arms 102 extend into close proximity with the liner 96. As illustrated in FIGURE 3, the arms 102 upon rotation extend into the conduit segments 84 and 86. A variable speed drive mechanism 106 is connected to shaft 1% in a suitable manner. With this arrangement the shaft rotates and transfers particulate material from the feeder inlet opening 76 to the outlet opening 78.

Operation The invention herein disclosed and described may be practiced as follows. Coal is supplied to the hoppers 14 by the coal bucket 10. Both the bin 28 and standpipe 36 are pressurized by the air supplied through conduit 38. To transfer a quantity of coal from hopper 14 to bin 20 the gate 3% between standpipe 36 and bin 20 is closed and the valve 46 in conduit 44 is closed. The valve 42 in conduit 46, however, remains open. Through suitable control means, hell or gate valve 22 is moved downwardly to provide an annular opening between bin 20 and hopper 14. The coal in hopper 14 is then fed by gravity into bin 20. The gate 22 is then closed and valve 40 is opened to again pressurize bin 20. To transfer the coal from bin 26 to standpipe 36, both valves 40 and 42 remain open and gate 33 is moved downwardly to transfer particulate coal by gravity from bin 20 to standpipe 36. With this arrangement standpipe 36 is maintained under substantially the same pressure as the pressure in conduit 50 and coal is transferred thereto from bin 2%) without loss of pressure in standpipe 36. The gates 22 and 30 are retained closed for a sufiicient length of time after the coal has been transferred from hopper 14 to bin 20 to permit the pressures within bin 20 and standpipe 36 to equalize.

The particulate coal under superatmospheric pressure is thus available at the inlet opening of the rotary feeder 48. Cold blast air is supplied through header 50 to conduit 84 and flows through conduit sections 84 and 86 to supply conduit 52. The air flowing through conduit segment 84 strikes the protuberance 94 to create eddy currents in the air stream.

When it is desired to introduce coal into the air stream and inject the coal into the tuyere zone of the blast fur nace, the drive mechanism 196 is energized to rotate the rotor 98. The pockets 104 adjacent the feeder opening 76 are filled with particulate coal at superatmospheric pressure. Rotation of the rotary feeder 8, preferably in a clockwise direction as illustrated in FIGURE 3, conveys the particulate coal within pockets 104 from the inlet opening 76 to the outlet opening 78. The eddy currents in the air stream created by protuberance 94 direct portions of the air stream upwardly to the pockets 104 to sweep the coal particles out of the respective pockets. The coal particles are fluidized in the air stream and are transferred as a fluidized stream through feed conduits 52 to the tuyeres 66. The fluidized stream of air and coal particles is thereafter introduced into the tuyere zone 60 of blast furnace 56.

Although a single supply conduit 52 is illustrated from the rotary feeder 48 to the furnace 60, it should be understood that suitable splitter devices may be employed to feed two or more tuyeres from a single rotary feeder.

With the above described apparatus it is now possible to introduce particulate coal at superatmospheric pres sure to a rotary feeder which, in turn, accurately meters the coal particles into a high pressure air stream. The rotary feeder having substantially equal inlet and outlet pressures is not subjected to the undue stresses present in known types of feeders and does not require elaborate and expensive sealing devices to maintain the high pressure differential between the feeder inlet and outlet.

According to the provisions of the patent statutes, the principle, preferred construction, and mode of operation of the invention have been explained, and what is now considered to represent its best embodiment has been h d i 5 illustrated and described. However, it should be understood that, Within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. Apparatus for injecting particulate material into a blast furnace comprising a rotary feeder having a cylindrical casing with a top inlet opening and a bottom outlet opening,

a rotor positioned in said casing and having a plurality of radially extending arms, said arms defining particulate material receiving pockets therebetween,

means to supply particulate material at superatmospheric pressure to said casing top inlet opening,

said casing bottom outlet opening terminating in a horizontal conduit and defining a gas inlet to said casing and a gas outlet therefrom, said radially extending arms extending into said horizontal conduit,

means for supplying gas at superatmospheric pressure to said conduit,

drive means to rotate said rotary feeder rotor at a preselected speed to convey preselected amounts of particulate material from said casing inlet opening through said casing outlet opening into said horizontal conduit,

said gas passing through said conduit and said casing at a sufiiciently high velocity to entrain said particulate material therein as a fluidized stream,

said conduit means arranged to convey said fluidized stream to the tuyere zone of a blast furnace, and

tuyere means in said blast furnace side Wall arranged to receive said fluidized stream and inject said fluidized stream into the tuyere zone of said blast furnace.

2. Apparatus for injecting coal particles into a blast furnace comprising a coal feeder having a cylindrical casing with a top inlet opening and a bottom outlet opening,

a rotor positioned in said casing and having a plurality of radially extending arms, said arms defining coal receiving pockets therebetween,

a standpipe connected to said cylindrical casing inlet opening,

said standpipe arranged to supply coal particles by gravity to said casing inlet opening,

means to pressurize said standpipe to superatmospheric pressure,

said casing bottom outlet opening terminating in a horizontal conduit and defining a gas inlet to said casing and a gas outlet therefrom, said radially extending arms extending into said horizontal conduit,

means for supplying gas at superatmospheric pressure to said conduit,

drive means to rotate said rotor at a preselected speed to convey preselected amounts of coal particles from said casing inlet opening through said casing outlet opening into said horizontal conduit,

said gas passing through said conduit and said casing at a sufliciently high velocity to entrain said coal particles therein as a fluidized stream,

said conduit means arranged to convey said fluidized stream to the tuyere zone of a blast furnace, and

tuyere means in said blast furnace side wall arranged to receive said fluidized stream and inject said fluidized stream into the tuyere zone of said blast furnace.

3. Apparatus for injecting coal particles into a blast furnace comprising a coal feeder having a cylindrical casing with a top inlet opening and a bottom outlet opening,

a rotor positioned in said casing and having a plurality of radially extending arms, said arms defining coal receiving pockets therebetween,

a bin positioned above said coal feeder and having an inlet opening and an outlet opening,

a standpipe connected at one end to said bin outlet opening and at the other end to said casing inlet opening,

said bin arranged to supply coal particles to said standpipe by gravity,

said standpipe arranged to supply coal particles by gravity to said coal feeder inlet opening,

first valve means closing said bin inlet opening,

means to pressurize both said bin and said standpipe to superatmospheric pressure,

said coal feeder casing bottom outlet opening terminating in a horizontal conduit and defining an air inlet to said casing and an air outlet therefrom, said radially extending arms extending into said horizontal conduit,

means to supply air at superatmospheric pressure to said conduit,

drive means to rotate said coal feeder rotor at a preselected speed to convey preselected amounts of coal particles from said casing inlet opening through said casing outlet opening into said horizontal conduit,

means to direct portions of said air upwardly into said casing,

said air passing through said conduit and said casing at a sufficiently high velocity to entrain said coal particles therein as a fluidized stream, said conduit means arranged to convey said fluidized stream to the tuyere zone of a blast furnace, and

tuyere means in said blast furnace side wall arranged to receive said fluidized stream and inject said fluidized stream into the tuyere zone of said blast furnace.

4. Apparatus for injecting particulate material into a blast furnace as set forth in claim 3 in which said means to pressurize said bin and said standpipe includes second conduit means connecting said first conduit means upstream of said coal feeder to said bin and said standpipe.

5. Apparatus for injecting particulate material into a blast furnace as set forth in claim 3 which includes a second valve means closing said bin outlet opening,

a hopper positioned above said bin and arranged to supply coal particles at atmospheric pressure to said bin,

and control means to open said first valve means and maintain said second valve means closed while said coal particles are transferred from said hopper to said bin and thereby maintain said standpipe at superatmospheric pressure, said control means arranged to maintain said first valve means closed while said coal particles are transferred from said bin to said standpipe so that said standpipe is maintained at a superatmospheric pressure.

6. Apparatus for injecting particulate material into a blast furnace comprising a rotary feeder having a cylindrical casing with a top inlet opening and a bottom outlet opening,

a conduit connected to the bottom of said casing and communicating with said casing outlet opening intermediate said conduit end portions,

a rotor positioned in said casing and having a plurality of radially extending arms,

said arms having end portions extending through said casing outlet opening into said conduit,

said arms defining particulate material receiving pockets therebetween,

means to supply particulate material at superatmospheric pressure to said casing top inlet opening,

means to supply gas at an elevated pressure to one end of said conduit,

said conduit bottom Wall having an upwardly extending protuberance adjacent to said casing bottom outlet opening, said protuberance arranged to direct portions of said gas flowing through said conduit upwardly into said rotor pockets,

drive means to rotate said rotor at a preselected speed to convey preselected amounts of particulate material from said casing inlet opening to said casing outlet opening,

said gas passing through said conduit at a sulficiently high velocity to entrain said particulate material therein as a fluidized stream,

other conduit means arranged to convey said fluidized stream to a tuyere zone of a blast furnace, and

tuyere means in said blast furnace side wall arranged to receive said fluidized stream from said last named conduit and inject said fluidized stream into the tuyere zone of a blast furnace.

7. Apparatus for injecting particulate material into a blast furnace as set forth in claim 6 which includes a liner of self-lubricating plastic material secured to the inner wall of said cylindrical casing.

8. Apparatus for injecting coal particles into a blast furnace comprising a rotary feeder having a cylindrical casing with a top inlet opening and a bottom outlet opening,

a conduit connected to the bottom of said casing and communicating with said casing outlet opening intermediate said conduit end portions,

a liner of self-lubricating plastic material secured to the inner wall of said cylindrical casing,

a rotor positioned in said casing and having a plurality of radially extending arms,

said arms having end portions extending through said casing outlet opening into said conduit,

said arms defining particulate material receiving pockets therebetween,

a bin positioned above said coal feeder and having an inlet opening and an outlet opening,

a standpipe connected at one end to said bin outlet opening and at the other end to said casing inlet opening,

a hopper positioned above said bin and arranged to supply coal particles at atmospheric pressure to said bin,

first valve means closing said bin inlet opening,

second valve means closing said bin outlet opening,

control means to open said firstvalve means and maintain said second valve means closed while said coal particles are transferred from said hopper to said bin,

said control means further arranged to maintain said first valve means closed while said particles are transferred from said bin to said standpipe,

means to pressurize both said bin and said standpipe to a superatmospheric pressure,

means to supply gas at an elevated pressure to one end of said conduit,

said conduit bottom wall having an upwardly extending protuberance adjacent to said casing bottom opening,

said protuberance arranged to direct portions of said gas flowing through said conduit upwardly into said rotor pockets,

drive means to rotate said rotor at a preselected speed to convey preselected amounts of coal particles from said coal feeder casing inlet opening to said casing outlet opening,

said gas passing through said conduit at a sufliciently high velocity to entrain said particulate material therein as a fluidized stream,

other conduit means arranged to convey said fluidized stream to a tuyere zone of a blast furnace, and

tuyere means in said blast furnace side wall arranged to receive said fluidized stream into the tuyere zone of a blast furnace.

References Cited by the Examiner UNITED STATES PATENTS 1,535,174 4/25 McGregor 7542 2,195,866 4/40 Le Clarick 266-28 X 2,511,017 6/50 Sherban 266-28 2,684,897 7/54 Diettrich 7541 40 DAVID L. RECK, Primary Examiner. 

1. APPARATUS FOR INJECTING PARTICULATE MATERIAL INTO A BLAST FURNACE COMPRISING A ROTARY FEEDER HAVING A CYLINDRICAL CASING WITH A TOP INLET OPENING HAD A BOTTOM OUTLET OPENING, A ROTOR POSITIONED IN SAID CASING AND HAVING A PLURALITY OF RADIALLY EXTENDING ARMS, SAID ARMS DEFINING PARTICULATE MATERIAL RECEIVING POCKETS THEREBETWEEN, MEANS TO SUPPLY PARTICULARE MATERIAL AT SUPERATMOSPHERIC PRESSURE TO SAID CASING TOP INLET OPENING, SAID CASING BOTTOM OUTLET OPENING TERMINATING IN A HORIZONTAL CONDUIT AND DEFINING A GAS INLET TO SAID CASING AND A GAS OUTLET THEREFROM, SAID RADIALLY EXTENDING ARMS EXTENDING INTO SAID HORIZONTAL CONDUIT, MEANS FOR SUPPLYING GAS AT SUPERATMOSPHERIC PRESSURE TO SAID CONDUIT, DRIVE MEANS TO ROTATE SAID ROTARY FEEDER ROTOR AT A PRESELECTED SPEED TO CONVEY PRESELECTED AMOUNTS OF PARTICULATE MATERIAL FROM SAID CASING INLET OPENING THROUGH SAID CASING OUTLET OPENING INTO SAID HORIZONTAL CONDUIT, SAID GAS PASSING THROUGH SAID CONDUIT AND SAID CASING AT A SUFFICIENTLY HIGH VELOCITY TO ENTRAIN SAID PARTICULATE MATERIAL THEREIN AS A FLUIDIZED STREAM, SAID CONDUIT MEANS ARRANGED TO CONVEY SAID FLUIDIZED STREAM TO THE TUYERE ZONE OF A BLAST FURNACE, AND TUYERE MEANS IN SAID BLAST FURNACE SAID WALL ARRANGED TO RECEIVE SAID FLUIDIZED STREAM AND INJECT SAID FLUIDIZED STREAM INTO THE TUYERE ZONE OF SAID BLAST FURNACE. 